Hydraulically actuated cranes



E. KIRSTEN 3,044,635

HYDRAULICALLY ACTUATED CRANES Filed July 17, 1959 July 17, 1962 &

H Inventor: B Er karcl' h ihslerz m ,MI6M Mask United States Patent 3,044,635 HYDRAULICALLY ACTUATED CRANES Erhard Kirsten, Kell, Kreis Drier, Germany Filed July 17, 1959, Ser. No. 827,902 Claims priority, application Germany Sept. 25, 1958 4 Claims. (Cl. 212-55) This invention relates to hydraulically actuated cranes having an inner jib telescopically displaceable in an outer jib to enable the degree of extension of the crane to be varied to suit requirements. In known forms of such cranes, the jibs were of a box-like, closed transverse cross section and it was necessary to locate the hydraulic systems required for the extension of the crane and for hoisting and lowering a load either above or below the outer jib.

It is an object of the present invention to make the construction of cranes of the form just referred to more compact and to achieve a saving of material and a reduction in weight.

According to the present invention, a hydraulically actuated crane comprises a first jib member of upwardly open transverse cross section, a second jib member telescopically displaced with respect to the first jib member and a hydraulically operated power system located within the first jib member for moving the second jib member longitudinally with respect to the first jib member.

Preferably, the second jib member is telescopically housed within the first jib member. The transverse cross section of the second jib may be of U or double-T form.

By way of example only, a rotary crane embodying the invention will now be described in greater detail with reference to the accompanying drawings of which:

FIG. 1 is a side elevation with parts of certain components removed, and,

FIG. 2 is a section on the line A--A of FIG. 1 on an enlarged scale.

The crane has an outer jib comprising a main member 1 and a mounting section 1a pivotally secured at 3 to a horizontal base plate 4 rotatable about a vertical axis 4a. The lower face of the base plate 4 is formed with inwardly extending gear teeth 5 in meshing engagement with a pinion '6 coupled to a hydraulically operated rack drive 7.

The main member 1 is of U-shaped transverse cross section as is shown in FIG. 2 and disposed telescopically within the member is an inner jib 2 also of U-shaped transverse cross section.

Displacement of the inner jib about the pivotal axis 3 is efiected by means of a hydraulically operated plunger 8.

Movement of the inner jib 2 with respect to the outer jib is effected by a hydraulic cylinder 9 mounted within and fixed to the outer jib member 1. The cylinder 9 has a movable ram 9' one end of which is secured to the inner jib 2.

For raising and lowering a load there is provided a cable 10 for example a rope which carries a hook 11 at one end and is operated by pulley systems 13 and 14- also mounted within the jib member 1 and operated by a hydraulic cylinder 12 Whose movable ram 12' controls the position of the pulley system 13. The system 13 comprises three pulleys freely rotatable on a U-shaped axle 13a on Whose ends are mounted rollers 15 movable in channel members 15 fixed to the sides of the jib member 1. In addition to guiding the roller 15' the channel members 15 assist in strengthening the jib 1. A transverse strut 18 assists in maintaining the strength and rigidity of the jib 2.

The inner jib 2 slides on roller 16 mounted in the lower part of the jib 1 as can be seen from FIG. 2. The jib 2 itself carries rollers 17 movable along the undersurface of the members 15. The rollers 17 facilitate movement of the jib 2 under conditions of load.

I claim:

1. A hydraulically actuated crane comprising a jib member of U-shape in cross section and arranged with the open side upwardly, a second jib member of U-shape in cross section and arranged to slide within the firstmentioned jib member, a U-shaped channel member secured to each leg of the first mentioned U-shaped member at the upper edges of the legs and mounted on the inside of the U, a plurality of rollers rotatably mounted on an axle with means at each end to contact in the U- shaped channel members to thereby guide the rollers, said U-shaped channel members also strengthening the sides of the first-mentioned U-shaped ji-b member, a hydraulic cylinder and piston in the first-mentioned jib member and connected to the plurality of rollers, and a hydraulic cylinder and piston in the first-mentioned jib member and connected to the jib members to adjust the second-mentioned jib member relative to the first-mentioned jib member.

2. A hydraulically actuated crane according to claim 1, in which a roller is mounted in the first-mentioned U- shaped jib member on which the second-mentioned jib member slides adjacent to the bottom portions of the U- shape of each jib member.

3. A hydraulically actuated crane according to claim 1, in which the axle is U-shaped so that the rollers thereon will be disposed within the first-mentioned jib member within the U-shape formation thereof.

4. A hydraulically actuated crane comprising a jib member of U-shape in cross section and arranged with its open side directed upwardly, a second jib member of U- shape in cross section arranged to slide within the firstmentioned jib member and having its open side directed upwardly, a hydraulic cylinder and piston provided and connected entirely within the first-mentioned jib member, and a second hydraulic cylinder and piston connected to both jib members and provided entirely Within both of said jib members, the second-mentioned hydraulic cylinder and piston being adapted to adjust the second-mentioned jib member relative to the first-mentioned jib member.

References Cited in the file of this patent UNITED STATES PATENTS 

